This invention relates to a fabric material, and more particularly, to a composite fabric having controlled wind permeability.
Conventional composite fabrics are designed to be fully wind resistant. By way of example, reference is made to U.S. Pat. Nos. 5,204,156; 5,268,212; and 5,364,678, all entitled “Windproof and Water Resistant Composite Fabric With Barrier Layer,” and which describe a drapable, stretchable, windproof, water resistant and water vapor-permeable composite fabric. This composite fabric includes an inner fabric layer 13A, an outer fabric layer 13B, and a barrier or membrane layer 17A (see FIG. 1). The barrier or membrane layer is constructed to prevent air and water from passing through the fabric layers. Testing has shown that the amount of air flowing through such a composite fabric is on the order or no more than 1 ft.3/ft.2/min.
The membrane or barrier of this type of prior art fabric composite is typically adhered or bonded to the fabric layers with the aid of an adhesive 18. The adhesive can be made from a polyurethane, polyester, acrylic or polyamide. Reference is made to FIG. 1, which illustrates the composite fabric of the prior art.
The above-described fabric composite is nonetheless less than desirable. Because such a composite fabric allows only minimal air flow therethrough, the wearer of the fabric may not be comfortable. When a person wearing a garment constructed with the composite fabric of the prior art performs some type of physical activity, heat is almost always generated, even if the outside air is cold. In order to adjust for this heat generation, the two fabric layers may be selected to have low insulative properties. However, this is disadvantageous, since using such a fabric composite will cause the wearer to feel cold when no activity is being performed.
Another disadvantage with prior art composite fabrics is the level of moisture vapor transmission. For example, a membrane made of polytetrafluroethylene, while having a higher moisture vapor transmission performance than a polyurethane membrane, is still not desirable, since it cannot handle a situation where high levels of moisture vapor or sweat are generated. As a result, wearer discomfort is often prevalent, due to this limitation on moisture transport. Specifically, excess moisture which could not be transported out from the fabric condenses next to the skin-side surface, producing a cold feeling on the skin of the person wearing a garment made from this type of prior art composite fabric.
Accordingly, it is desirable to provide an improved windproof, water vapor permeable fabric which eliminates the problems associated with prior art fabrics.